1. Field of the Invention
The present invention relates to a closure device, and more particularly to a closure device suitably used for opening and closing a window, sun-roof panel, etc., of an automobile or the like.
2. Statement of the Related Art
A power window regulator, which has become popular in recent years, for use on, for example, passenger cars, will be described as an example of the conventional closure device of this type.
As a mechanism for raising and lowering window glass, the X-arm system, the tape system, the wire system, etc. are adopted for the conventional power windows, and in the respective cases a drive motor is fixed to a door body.
In the X-arm system, the X-arm is moved vertically by the drive motor. In the case of the tape system and the wire system, on the other hand, the window glass is opened or closed by taking up or paying out the tape or wire by the drive motor.
With the above-described mechanisms, the following drawbacks have been encountered:
(1) Since the mechanism takes up practically the entire inner space of the door, it is difficult to mount door lock parts and others in the limited space of the door interior, and it is difficult to make the door thin. In particular, the number of parts accommodated inside the door has increased in recent years, so that if this mechanism is adopted, restrictions are inevitably imposed on special functions of door portions.
(2) In the X-arm system, numerous regulator parts are used, and since most of these parts are made of metal in view of the strength, it has been difficult to adopt lightweight drive portions. In addition, since the driving efficiency is poor, it has been necessary to use a motor having a large torque.
(3) In the case of the tape system and the wire system, it is possible to make the parts lightweight as compared with the aforementioned X-arm system, but since the tape or wire is bent, durability has been unsatisfactory. In addition, since the driving efficiency is poor as in the case of the X-arm system, a large-torque motor has been similarly required.
Accordingly, to solve such problems, improvements have been proposed to permit a substantial reduction in the number of parts used by causing the drive motor to move together with the window glass, thereby making it possible to make effective use of the inner space of the door.
These proposals are disclosed in, for instance, Japanese Utility Model Laid-Open No. 68284/1985 and Japanese Patent Laid-Open No. 286485/1986, but the arrangement of Japanese Utility Model Laid-Open No. 68284/1985 will be described herein by way of example.
As shown in FIG. 8, the power window disclosed in this publication comprises a glass holder 12 fixed to the lower end of a window glass 10, a reversible motor 14 fixed to the glass holder 12, a pinion gear 18 rotatively driven by the motor 14 via a worm gear 16, and a rack 20 fixed vertically to an inner panel of the door and meshing with the pinion gear 18.
In accordance with this power window, since a system is adopted in which the window is driven by the rack 20 and the pinion gear 18, the number of parts used is small. In addition, since only the rack 20 is fixed vertically to the inner panel of the door, it is possible to make effective use of the inner space of the door.
However, with the above-described power window employing the rack-and pinion system, although it is possible to overcome the drawbacks experienced with the conventionally available X-arm system and the like, new problems have emerged, as will be described below.
In other words, in the system shown in FIG. 8, as shown in FIG. 9 in which the mechanism shown in FIG. 8 is viewed in the direction of arrow A in the drawing, distance L2 between the central line of a window glass 10, i.e., an operating point, and a central line of the rack and pinion assembly which generates a driving force for vertically driving the window glass 10 becomes large as it is restricted by the thickness of the glass holder 12, motor 14, and pinion gear 18 that are sequentially superposed on each other. Accordingly, in addition to the vertical driving force, angular moment proportional to the aforementioned distance L2 acts on the window glass 10, i.e., a closure member, and the driving efficiency has therefore been appreciably aggravated.
In consequence, at the time of opening or closing the window glass 10, a frictional force attributable to the aforementioned angular moment constantly acts on the window glass 10, so that there has been a problem in that, in order to obtain a positive opening and closing operation, a torque which is more than is necessary is required of the motor 14.
Furthermore, since the motor 14 is disposed at a position offset from the path of travel of the closure member, the motor 14 which has a substantial weight exerts an eccentric load on the closure member, so that there has been another problem in that the aforementioned frictional force is disadvantageously increased.
Moreover, as described above, since the arrangement is such that the glass holder 12 motor 14, and pinion gear 18 are superposed sequentially on each other, there has been a further problem in that these members occupy the inner space of the door in the direction of the thickness of the door.